If you go to the original post [0], he provides a link to the maze in question [1] which clearly states at the bottom of every page "© 2010 KrazyDad.com". How much clearer can that be?
[0] http://krazydad.com/blog/2014/07/13/hmm-this-maze-looks-fami... [1] http://krazydad.com/mazes/sfiles/KD_Mazes_IM_v1.pdf